Which of the following is a type of telehealth?

Privacy filters are devices designed to restrict viewing angles on screens to protect sensitive information from being seen by unauthorized individuals. While they may enhance privacy in telehealth settings, they do not constitute a form of telehealth themselves, as they do not involve the exchange of health information or patient monitoring.

A patient portal is an online platform that allows patients to access their health information, schedule appointments, and communicate with healthcare providers. While it facilitates communication and access to health information, it is a supportive tool rather than a direct method of delivering healthcare services like remote patient monitoring.

Email correspondence can be used for communication between patients and healthcare providers; however, it is not a formal type of telehealth. While it can facilitate some aspects of care, it lacks the comprehensive monitoring features characteristic of telehealth practices such as remote patient monitoring.